High freuqnecy tape recorder



Oct. 6, 1959 L. DAWKINS HIGH FREQUENCY TAPE RECORDER 2 SheetS Sheet 1 Original Filed Oct. 20, 1955 INVENTOR fit f ATTORNEYS v A. 5 x w h. J N .Jd I/J/ L w n J n--- n i .4 4- I l 1 1: 1 H A v Oct. 6, 1959 1.. DAWKINS HIGH FREQUENCY TAPE RECORDER Original Filed Oct. 20, 1955 2 Sheets-Sheet 2 W 7 v V INVENTOR ATTORNEY5 United States Patent 2,901,572 men FREQUENCY TAPE RECORDER Lacy L. Dawkins, Cary, NC.

1 cl im. (or. 274-41.4

This invention pertains to magnetic tape recording apparatus generally, and more specifically ;to apparatus for recording a large amount of information on magnetic tape at high relative speed between the recording head and the recording medium. This application is a ,divisional application of my earlier-filed parent application Serial No. 541,588, filed October 20, 1955, which application issued as U.S. Patent Nop2,829,208 on April 1, 1958.

' It is well known in the magneticrecording art that there are certain limitations to the use and fidelity of reproduction of the recordings. For example, the top frequency that can be reproduced is, among other things, a function of the relative speed between the record and the reproducing head. The fidelity of reproduction may be greatly improved by increasing the relative speedof the recording head with? respect to the record. The

U.S. patent to Berens #2,66l,397 discloses a magneticv recording apparatus wherein the recording head and the reproducing head are mounted for movement in a direction opposite to the direction of movement of the magnetic tape, to thereby produce a relative movement between the recording heador .reproducing head and the tape to obtaina higher relative speed during recording. Rotating recording heads are similarly shown by the patents to Cooley #2,690,473 and Gunby #2,611,828. My invention consists of an improved method'of magnetic tape recording wherein the relative speed of the magnetic material with respect to the recording head is increased.

Thus an object-of my invention is to provide an improved magnetic tape recording apparatus which will obtain high relative speed between'the recording head and the magnetic tape record with slow longitudinal movement of the tape.

Another object of my invention is to provide an improved magnetic tape recording apparatus which will 7 obtain high relativespeed between the recording head and the magnetic tape record for a long-playing record of standard length with slow longitudinal movement of the tape.

Another object of my invention is to provide a magnetic tape recording apparatus which will spirally record a sound and/or video or other information track on a continuously moving magnetic tape.

A further object of my invention is to continuously record a spiral sound and/ or video or other information track across a magnetic tape when the tape is temporarily formed into a tubular shape as it travels longitudinally through the recorder.

A still further object of my invention is to provide a magnetic tape with serrated edges in combination with a tape feeding mechanism which will temporarily form the tape into a tubular configuration with the serrated tape edges intermeshing to provide alignment of the edges and to prevent slippage.

With the above and other objects in view, the invention will be hereinafter more particularly described, and the combination and arrangement of parts will be shown in the accompanying drawings and pointed out in the claim which forms a part of this specification.

Reference will now be had to the drawings, in which:

Figure 1 is a side elevational view of the magnetic tape recording apparatus including the feeding and take-up apparatus.

Figure 2 is a longitudinal cross-section of the recorder.

Figure 2 is a cross-section view of the recorder taken at 33.

Figure 4 is a perspective view of a section of tape shaped into tubular form.

Figure 5 is a cross-section of the tape shaper rollers.

Referring to Figure l, the fiat magnetic tape is wound upon the tape supply reel 1. During the recording process, the magnetic tape 2 iscontinuously unwound from the supply reel and passes through the supply reel takeup tension mechanism shown generally at 3, where the desired tension is applied to the moving tape. The tape is then fed to the tape shaping rollers 4 and S where, as will be later described, the tape is begun to be shaped into a tubular configuration, the edges of the tape being gradually brought together to form atube. The tape in approximately tubular form enters the recorder 6. A revolving recorder records a spiral track across the inner surface of the longitudinally-moving tubular-formed tape. The tape leaves the recorder in the tubular form, passes through the tape shaping rollers 7 and 8, and is returned to its normal flat configuration. The tape then passes through the horizontal capstan 9, which provides traction for motivating the tape through the apparatus, through the tape-up tension mechanism 10, and thence to the take-up or storage reel 11. The supply reel 1 may be provided with a rewind motor whereby during the rewinding process, the tape passes from the take-up reel to the supply reelinthe reverse direction through the recording apparatus.

Referring now to Figure 2, the recorder consists of a stationary cylinder 12, rigidly supported by supporting brackets 13 and 14. Secured to the brackets 13 and 14 are arms 15 and 16 which support brackets 17 and 18. Mounted inbrackets 17 and 18 are stationary inner cylinders 19 and 20. Rotatably mounted in bearings 21 secured to the inside surfaces of inner cylinders 19 and 20 is recording shaft 22. Rigidly secured to the rotary recording shaft are mounting arms 23 and 24 which carry the recording head 25 and the monitoring pick-up head 26. The monitoring pick-up head follows the recording head by degrees on the rotating shaft and acts as a balance against the weight of the recording head, allowing more uniform spacing between recording head and tape. The monitoring head allows the operator to make a check on the recording one-half revolution behind the actual recording. A micrometer screw adjusting mechanism, not shown, provides means for minutely adjusting the position of the recording and monitoring heads with respect to the linear dimension of the tape, enabling the exact placement of the monitor on the pick-up track when operated for playback. The monitor head is offset half the width of a recorded track so that it follows exactly in the path of the recording head instead of a half track behind.

Tape guide rollers 27 are secured to the stationary inner cylinders 19 and 20 by means of supporting members 27a. A small clearance is provided between the inner surface of stationary cylinder 12 and the rollers 27. Thus the tape in tubular form continuously passes through the recorder between the rollers 27 and the inner surface of the cylinder 12. Since the recording head 25 is continuously rotated on the inner surface of the longitudinally moving temporarily formed tubular magnetic tape, a spiral track will be made across the tape. Thus for relatively slow longitudinal movement of the inner surface of the temporarily-formed tubular tape to provide the desired higherrelative speed between the recording head and the tape. Figure 3 shows the clear ance between rollers 27 and the inner surface of cylinder 12, allowing passage for the tubularly-formed tape 2..

Referring to Figure 4, the tape may be provided with serrated edges 28 with a flanged flap-:29. The tape may be provided with a slot 30 to cooperate withthe tape guide 31 (Figure 3). Thus the combination of the serrated edges, and the tape guide and slot means, functions to orient the tape in-the recorder, preventslippage, and to aid in forming the tubular configuration. The

flap 29 functions to provide a smooth inside surface to the recording head. a

As seen in Figure 5, the tape shaper roller 4 has an elliptical cross section, while the corresponding shaper roller has a cross-section wide at the extremities and tapering to a narrow portion at the middle, so that tape passing between the rollers will be formed into a halfcylinder with approximatety U-shaped cross section. The

roller shafts 32 are mounted in bearings 33 in supports 34. It is the passage through the tape-shaper rollers that begins the forming of the tubular configuration.

Thus in operation, the flat tape is slowly fed from the supply reel, through the tape tensioning device, to the tape shaping rollers where the forming of the tape into the tubular configuration is commenced, the side edges being curled up gradually until the serrated edges meet" and cooperate to form a tube as the tape passes through the center of the recorder. There the recording head r'e volving at a high rate of speed records a spiral track inside the tube of tape. The tube then passes through the second set of tape shaper rollers 'where it emerges as a flat strip again, through the capstan and take-up tension I mechanism, and finally to the storage take-up reel.

The magnetic tape could be of any convenient Width and length. If the tape were, made 25 inches wide then each revolution of the recording head-would expose 25 inches of magnetic track. If the heads were revoi ved four times per second, for instance, then 100 inches of magnetic tape would be exposed per second The lateral motion of tape feed could be adjusted through the recorder as desired. The horizontal capstan which provides tape traction-can be driven by a synchronous motor which is synchronized with the motor driving the rotating re-,

The frequency range of the system utilizing a revolving recording head on the insideof thetubular section of magnetic tape is on the order of 30,000,000 cycles per second, or possibly well up in the VHF range. Since television video signal frequencies are presently confined to a maximum value of 4,000,000 cycles per second, the forward movement ofvtape feed could be held to a value which would permit hours of TVprogram recording or play-back on a single reel of tape. "Thus it may be seen .thatvmy device is particularly applicable where there is a need for a long-playing record. While in accordance with the provisions of the'statiites,

'] haveillustrated and described the best form offembodiment of my invention now known to me, it-will be apparent to those skilled in the art that changes may be made in the form of the apparatus described without departing from the spirit of my invention as set forth in the appended claim.

What I claim is: Y

A magnetic record for use in magnetic tape recording apparatus comprising a normally flat'tape of flexible magnetic material; said tape having planar upper andlower surfaces and serrated lateral edge portions, the serrations having a continuous flap portion extending from the ;lower portion thereof longitudinally the length of the I tape whereby when a portion of the tape is formed into a tubular configuration with the serrated edge portions in engagement said flap will extend into said cut-out pertion to cover the serrations to provide a smooth-inner surface of the tubular portion, said tape also having a slot in the lower surface'thereofextending longitudinally the length of the tape to provide means for orienting the tape in the magnetic tape recording apparatus.

References Cited in the file of this patent UNITED STATES PATENTS Austria I Feb. .10, 

